Compensation Method for Engine Torque Fluctuation of Hybrid Electric Vehicle

Abstract

The invention discloses a hybrid electric vehicle engine torque fluctuation compensation method. The hybrid electric vehicle engine torque fluctuation compensation method guarantees that the compensation torque frequency is the same as the engine torque fluctuation frequency according to the position where an engine rotor is located, within the range of the torque output by an ISG system, engine torque compensation control is adopted, namely torque which inversely fluctuates along with the torque of an engine is overlaid on a torque command of the ISG system so that a part of torque fluctuations of the engine can be counteracted by the torque output by the ISG system, and therefore the synthesis torque fluctuations of a power system are reduced. Accordingly, the torque fluctuations of the power system can be reduced, and therefore the vibration and the noise of the power system are reduced.

Description

technical field [0001] The invention relates to the technical field of automobile engines, in particular to a method for compensating engine torque fluctuations of hybrid electric vehicles. Background technique [0002] The grim situation of global energy and the environment, especially the huge impact of the international financial crisis on the automobile industry, has pushed countries around the world to accelerate the strategic transformation of transportation energy. New energy vehicles represented by hybrid vehicles, pure electric vehicles and fuel cell vehicles have become the future vehicles important direction of development. [0003] Electric vehicles are currently facing difficulties such as short driving range, expensive batteries, and imperfect infrastructure. Automobile is of great significance to the development of my country's automobile industry. This means that for a long period of time, the powertrain of new energy vehicles will consist of lower power eng...

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Problems solved by technology

[0004] The torque fluctuation of a traditional engine within a working cycle is relatively large. Taking the four-cylinder engine most commonly used in domestic compact cars as an example, such as Figure 1 The approximate torque waveform curve of one circle (360 degrees) of the engine shown, the peak average torque is 150Nm, but the torque changes from 530Nm to -110Nm, the torque fluctuation is large, causing large vibration and noise, and affecting system efficiency

This defect is difficult to completely overcome in traditional cars that simply use the engine as the powertrain.

[0005] While the traditional vehicle hybrid power system, although the integrated design of the power system components such as the engine and the motor is realized mechanically, the torque output of the whole power system is relatively independent.

For example, the ISG motor and the engine have achieved a high degree of mechanical integration, but the torque control of the ISG (Integrated Starter and Generator) system uses the output torque to follow the command torque. In one engine cycle, the output torque of the ISG system is approximately a straight line. This control method does not improve the above-mentioned defects of the traditional engine, and because of the vibration and noise of the motor system itself, the vibration and noise of the hybrid electric vehicle power system equipped with ISG are higher than those of the traditional vehicle power system.

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